1. Field of Invention
This invention relates to portable systems capable of acquisitioning, displaying, and recording physiological information obtained from a human subject.
2. Description of Prior Art
Medical clinicians often need to assess physiological information from a human subject in order to diagnose or monitor disease states. In clinical outpatient environments, the scope of this information widely ranges from cardiac information (i.e. ElectroCardioGrams [ECGs]) to pulmonary information (i.e. Pulmonary Function Tests [PFTs], pulse oximetry [S.sub.a O.sub.2 ]) to neurologic information (i.e. ElectroEncephaloGrams [EEGs], nerve conduction studies).
Current devices used to assess such physiological information are commonly available to clinicians and exist in numerous configurations. Typically, most of these configurations consist of a single device that assesses a single or related group of physiological parameters. This device is usually dedicated only to the acquisition of physiological information for one organ system of the human subject that is being tested. Typical examples of these devices include the electrocardiogram and the pulmonary function test. A few devices acquisition information from more than one organ system such as the PROPAQ System (U.S. Pat. No. 5,568,814 [1996]) manufactured by PROTOCOL Systems, Inc. which is capable of recording electrocardiograms, oxygen saturation, and blood pressure. These multiorgan, physiological monitoring systems are useful in portable/ambulatory situations where temporary monitoring of multiple physiologic parameters is required but, such systems lack utility in clinical outpatient environments where more parameters may be required to be assessed and where these parameters need to be integrated into the patients medical record.
Current devices are typically electrically powered from commercial power found in most office environments. Some devices are battery powered for portable operation such as the PROPAQ device mentioned above. The utility of portability of such devices is attained when the device is battery powered and many situations in a clinical outpatient environment benefit from this portability by having equipment that can be easily moved from one setting to another. An example of such utility is seen in today's portable finger pulse oximeters.
Current devices are limited in their ability to transmit their acquired information to locations where that information could be best utilized or stored. The predominant method of data storage is the hand-copying of the acquired information from the device to the patient's medical record (e.g. a blood pressure measurement or a finger oximeter measurement). Alternatively, the device may print either a strip or a page of paper which is retrieved and placed in the medical record. Both of these methods fail to "integrate" the information into the patient's medical record in a manner that is timely, that maximizes its utility there, and that minimizes loses of such acquired information.
The majority of devices used to collect physiological information from a human subject utilize electrical circuitry that must convert a transduced signal into a digital value (i.e. analog-to-digital conversion) which is then usually manipulated by a digital processing element (i.e. microprocessor,or digital signal processor) into either displayable information, and/or a transmittable/storable element. Since the majority of devices utilize this method, it would seem reasonable if these devices could share their common conversion and manipulation elements by combining them into a common unit. This would offer significant cost advantages in the common unit as compared to the individual devices since redundant electrical hardware is shared among the signals to be transduced and manipulated.
Furthermore, alphanumeric as well as graphical information is commonly generated by these devices and is typically displayed on the front panel of such devices or is printed on paper medium. It would also be reasonable to share a common display device in a unit that would contain functions combining various measurement parameters so that a cost advantage could be obtained by sharing this common display device. This concept of sharing of the display device could also be extended to the sharing of a common printing device, again, achieving further cost advantages.
Additionally, certain medical conditions could be diagnosed in the clinical outpatient environment if multiple and/or continuous monitoring of certain physiological parameters could be performed. Examples of these conditions include sleep apnea, dysrhythmias, and certain neurological/psychiatric conditions. It would be advantageous to be able to monitor and record these parameters within the clinical outpatient environment, and diagnose/monitor these medical conditions in this environment rather than having to send the subject to specialized centers needed to diagnose/monitor these conditions. Having these capabilities within the clinical outpatient environment could offer expense savings to our healthcare system.
As more and more medical information is collected on a particular human subject over the course of his/her medical history, the need to centrally collect this information, organize it, store it, and transmit it to other locations becomes a more difficult task. Currently, in the clinical outpatient environment at least, these tasks are manually performed. There is a paucity of systems that efficiently organize and store such information. A need exists for a system that can accomplish the above tasks that utilizes a cost effective system.
Several types of monitoring systems that acquisition multiple physiologic parameters are currently employed within inpatient as well as outpatient clinical environments. Many of these, such as in U.S. Pat. No. 4,860,759 (1989), are intended only to continuously monitor and display certain groups of physiological parameters. Others, such as U.S. Pat. Nos. 5,263,491 (1993), 5,275,159 (1994), 5,238,001 (1993), and 5,339,821 (1994) continuously monitor and log certain groups of physiological parameters for future playback and analysis, but, do not display the information while it is being acquisitioned. Still, other systems such as described in U.S. Pat. Nos. 4,686,998 (1987), 4,827,943 (1989), 5,012,411 (1991), 4,974,607 (1990), 4,889,131 (1989), and 5,257,627 (1993) continuously monitor certain groups of physiological parameters and transmit the information to remote sites for decision making. None of the above systems describe a system to acquisition selected physiological parameters in a clinical outpatient environment and display this information on a viewing device, as well as incorporate the information into the medical record, and, interpret and store this information at the collection site.
Other physiological monitoring systems described in U.S. Pat. Nos. 5,375,604 (1994) and 5,417,222 (1995) are either portable, multichannel systems for monitoring only (i.e. not intended to permanently record the data into a human subject's medical record) (the former patent) or bedside/intensive care type units with nonportable beside sensors (the latter patent). Both of these devices are also intended to transmit information to a central station for analysis and logging of this information at this location, but not at the bedside.
A few other relatively new systems (of particular interest is the "NAS" system from BCI International; no patent found at this time) are ambulatory monitoring systems with a limited number of physiological parameters that can be monitored and whose parameters can only be viewed statically (i.e. the device does not provide continuous monitoring of the physiologic variable of interest). These devices utilize a personal computer to acquisition and display static parameters only. Integration of the information into the patient's medical record is not a capability of these types of systems.
Technological advances in personal computers, especially portable personal computers, now allow many systems access to processing capabilities not available in the past. Portable personal computers now have ample processing power to allow them to control external systems in a real-time fashion. These computers also allow a system to utilize their display and keyboard for very sophisticated user interaction as well as information displays. Furthermore, these computers offer very large temporary, as well as long-term storage capabilities, that allow for management of large databases of information. These systems also allow for simplified communication of information to/from remote computing facilities. Finally, these portable computers are battery powered and allow for remote processing/control of an application where commercial power is not available. The numerous capabilities of personal portable computers present a very cost effective method of controlling and interacting with external systems that has otherwise not been available in the past.
Although many patient physiological monitoring systems currently exist, most of these are not appropriate for the measurement and management of physiological parameters of human subjects in the clinical outpatient environment. This environment demands the ability to monitor more physiological parameters than current systems offer within one system. The acquisition of these parameters from human subjects needs to be integrated into the patient's medical record in a timely, efficient, and reliable manner. The acquisition process should have the capability of being performed without the use of commercial power and the equipment used should be easily portable between various environments. Because the various subsystems used to acquisition physiological parameters utilize similar electrical components, a system incorporating these various subsystems should take advantage of the sharing of these components in an effort to minimize the cost of the overall system. The physiological monitoring system described in this document incorporates the above concepts into an apparatus for monitoring physiological parameters that has very high utility and low cost in a clinical outpatient environment.